US is second-biggest polluter in the world

A plume of steam billows from the coal-fired Merrimack Station in Bow, New Hampshire, as President Barack Obama unveiled his unprecedented regulations clamping down on carbon dioxide emissions from existing US power plants. Photo: AP

If some observers were shocked by the scope of President Obama's proposed climate Bill cuts they shouldn't be.

America's power stations, many of which are coal-powered, account for a startling 5pc of all global carbon emissions.

The truth is that while the White House hails the "historic steps" taken to fight climate change under Mr Obama, the US still has a long way to go.

America is second only to China in terms of carbon emissions, and emits significantly more than the entirety of the EU.

And while US emissions have fallen from their peak in 2005, they have since plateaued, and actually increased between 2012 and 2013.

The regulations announced yesterday are intended to spur investment in renewable sources of electricity.

At present, 39pc of US electricity comes from coal, with natural gas accounting for another 27pc.

Opponents will argue that the EPA is seeking "to completely restructure the US energy markets in the way energy is generated and dispatched," said Thomas Lorenzen, a former government lawyer on clean-air cases now with Crowell & Moring in Washington.

The Supreme Court has said the agency is "treading on thin ice when it comes to regulating wide sections of the economy without clear congressional authorisation," he said.